PROJECT SUMMARY/ABSTRACT The persistence of risky drinking among young adults in college calls for continued efforts to prevent harms related to alcohol. Current prevention interventions have achieved some success, but rely on a single mechanism of change: correcting exaggerated drinking norms. We propose to test a novel prevention strategy targeting another mechanism of change: creating attitude-behavior dissonance. To date, changing alcohol- related attitudes and the resulting attitude-behavior discrepancy has been underutilized as a behavior change strategy for alcohol abuse prevention. Informed by an extensive literature showing strong and consistent associations between alcohol attitudes and drinking behavior, we adapted a brief counter-attitudinal advocacy (CAA) manipulation to the alcohol prevention context. Briefly, CAA asks participants to engage in an activity in a way that is contrary to an existing attitude or behavior and are hypothesized to experience dissonance (e.g., an individual who experiences alcohol-related consequences describes how he/she can avoid those consequences and why avoiding those consequences is a positive approach to alcohol use). This dissonance may be reduced by changing future behavior or attitudes. The goals of the proposed research are to demonstrate the utility of CAA to change high volume drinking and related consequences and evaluate two hypothesized mechanisms of action, attitude change and attitude-behavior dissonance. We propose a small RCT with an experimental condition and a control condition to determine the impact of CAA on alcohol outcomes and hypothesized mediators. We will recruit 200 heavy drinking students who endorse >2 alcohol- related consequences in the previous month. Based on pilot work, we designed a prompt to elicit counter- attitudinal statements in favor of reducing alcohol-related consequences. We will test hypotheses that, relative to attention control, the attitude change manipulation will increase positive moderation attitudes; decrease positive heavy drinking attitudes; increase attitude-behavior dissonance; decrease drinks per drinking day, heavy drinking frequency, and alcohol consequences. We will evaluate the hypothesized mediators (attitudes, dissonance) at post-test, and will collect alcohol outcomes at 1- and 3-month follow-ups. This study will demonstrate the generalizability of attitude change theory and CAA methods to the alcohol prevention context. A study derived from CAA will advance prevention science in two definitive ways. First, changing alcohol attitudes to induce attitude-behavior discrepancy represents an understudied mechanism of alcohol use behavior change. Considering attitudes are a central driver of behavior, it is striking that CAA and similar approaches are underutilized in the alcohol intervention literature. Second, the specific elements of effective CAA approaches involve prompting participants to generate behavioral solutions that they themselves could use in drinking situations. Implications for the public health include establishing the efficacy of a new approach for reducing high volume drinking and related consequences among young adults engaging in at-risk drinking.